WebGPURenderer: Fallback for alphaToCoverage if antialias is disabled (#29395)

* WebGPURenderer: Fallback for alphaToCoverage if antialias is disabled

* handle line node material too

src/materials/nodes/InstancedPointsNodeMaterial.js

@@ -39,21 +39,19 @@ class InstancedPointsNodeMaterial extends NodeMaterial {
 
 		this.setDefaultValues( _defaultValues );
 
-		this.setupShaders();
-
 		this.setValues( params );
 
 	}
 
 	setup( builder ) {
 
-		this.setupShaders();
+		this.setupShaders( builder );
 
 		super.setup( builder );
 
 	}
 
-	setupShaders() {
+	setupShaders( { renderer } ) {
 
 		const useAlphaToCoverage = this.alphaToCoverage;
 		const useColor = this.useColor;
@@ -94,7 +92,7 @@ class InstancedPointsNodeMaterial extends NodeMaterial {
 
 			const len2 = lengthSq( uv().mul( 2 ).sub( 1 ) );
 
-			if ( useAlphaToCoverage ) {
+			if ( useAlphaToCoverage && renderer.samples > 1 ) {
 
 				const dlen = float( len2.fwidth() ).toVar();
 

src/materials/nodes/Line2NodeMaterial.js

@@ -52,13 +52,13 @@ class Line2NodeMaterial extends NodeMaterial {
 
 	setup( builder ) {
 
-		this.setupShaders();
+		this.setupShaders( builder );
 
 		super.setup( builder );
 
 	}
 
-	setupShaders() {
+	setupShaders( { renderer } ) {
 
 		const useAlphaToCoverage = this.alphaToCoverage;
 		const useColor = this.useColor;
@@ -299,7 +299,7 @@ class Line2NodeMaterial extends NodeMaterial {
 
 				if ( ! useDash ) {
 
-					if ( useAlphaToCoverage ) {
+					if ( useAlphaToCoverage && renderer.samples > 1 ) {
 
 						const dnorm = norm.fwidth();
 						alpha.assign( smoothstep( dnorm.negate().add( 0.5 ), dnorm.add( 0.5 ), norm ).oneMinus() );
@@ -316,7 +316,7 @@ class Line2NodeMaterial extends NodeMaterial {
 
 				// round endcaps
 
-				if ( useAlphaToCoverage ) {
+				if ( useAlphaToCoverage && renderer.samples > 1 ) {
 
 					const a = vUv.x;
 					const b = vUv.y.greaterThan( 0.0 ).select( vUv.y.sub( 1.0 ), vUv.y.add( 1.0 ) );

src/materials/nodes/NodeMaterial.js

@@ -194,7 +194,9 @@ class NodeMaterial extends Material {
 
 		if ( globalClippingCount || localClippingCount ) {
 
-			if ( this.alphaToCoverage ) {
+			const samples = builder.renderer.samples;
+
+			if ( this.alphaToCoverage && samples > 1 ) {
 
 				// to be added to flow when the color/alpha value has been determined
 				result = clippingAlpha();

src/renderers/webgl-fallback/utils/WebGLState.js

@@ -512,7 +512,7 @@ class WebGLState {
 
 		this.setPolygonOffset( material.polygonOffset, material.polygonOffsetFactor, material.polygonOffsetUnits );
 
-		material.alphaToCoverage === true
+		material.alphaToCoverage === true && this.backend.renderer.samples > 1
 			? this.enable( gl.SAMPLE_ALPHA_TO_COVERAGE )
 			: this.disable( gl.SAMPLE_ALPHA_TO_COVERAGE );
 

src/renderers/webgpu/utils/WebGPUPipelineUtils.js

@@ -138,7 +138,7 @@ class WebGPUPipelineUtils {
 			},
 			multisample: {
 				count: sampleCount,
-				alphaToCoverageEnabled: material.alphaToCoverage
+				alphaToCoverageEnabled: material.alphaToCoverage && sampleCount > 1
 			},
 			layout: device.createPipelineLayout( {
 				bindGroupLayouts